A method for reducing gastrointestinal inflammation, enhancing growth, or improving feed efficiency in a human or non-human animal is disclosed. The method involves administering to the animal an agent that can reduce the formation of the signal transduction complex of endotoxin, TLR4 and CD14 on the cellular surface of a cell in the gastrointestinal tract of the animal. In a preferred embodiment, an antibody against the extracellular domain of TLR4 or CD14 is used to reduce the formation of the complex. A composition that contains the antibody and an ingestible carrier is also disclosed. Further disclosed is a method for producing a peptide for enhancing growth, improving feed efficiency, or both in a human or non-human animal.